Organic versus conventional foods: are they really better for people’s health? Are all organic foods created equal, and if not, which do we pick and why do we pick them? These seemingly simple questions are fraught with a barrage of personal and political beliefs and values. Yet the voice of reason that is often missing from the conversation is science.

One reason for this knowledge gap is that studies involving dietary intervention (i.e., replacing conventionally produced foods with organic foods) usually are only conducted for one- to two-week periods on small populations. This period of time isn’t long enough to provide conclusive evidence that a test group became healthier on an organic diet.

That’s why Cynthia Curl, an assistant professor in Boise State’s Department of Community and Environmental Health, has conducted what is believed to be the first ever long-term diet intervention study on the effects of organic produce on pregnant women. Results of the Treasure Valley study revealed that adding organic produce to an individual’s diet, as compared to conventional produce, significantly reduced exposure to pyrethroid insecticides – that is, insecticides that are neurotoxic to insects as well as humans in large enough doses.

For six months, spanning 20 women’s second and third trimesters, Curl’s two study groups were provided with weekly deliveries of fresh fruits and vegetables. One group was given organic produce while the other received conventional produce. Weekly urine samples were collected from both groups and analyzed by the Center for Disease Control. The results showed that women consuming organic produce had significantly lower pesticide metabolites.

“This research is novel because it’s also the first study done in pregnant women, and there’s a lot of research showing that time in-utero is a sensitive time for development,” said Curl. “So if we were to look for a health effect from decreasing pesticide exposure, one of the places we might see it — if it exists — is in this population.”

[Editor’s note: Most research shows that pesticide exposure from food, organic or conventional, poses no health risk. Read GLP’s FAQ Are organic foods healthier than conventional foods? to learn more.]

This study also proves the feasibility of conducting long-term organic diet intervention study among pregnant women. Curl believes that by following this study’s parameters with a much larger test group, and then monitoring the health and development of the children after birth, it would be possible to conclusively answer the question of whether there is a measurable health benefit to children if their mothers consume organic, rather than conventional, food during pregnancy.

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This study also demonstrates that it is not necessary to consume a fully organic diet in order to experience a significant change in pesticide exposure. By supplementing participants’ diets with organic fruits and vegetables, the authors better imitated how many people actually consume organic food – as a part of their diet rather than the whole.

“Even as we learn more about the pesticide exposure that we might be getting from our diets, it’s important to put that in the right context and understand that the first order is to eat as many fruits and vegetables as possible,” said Curl. “If there are pesticides that are in our food supply at levels that would lead to negative health effects, the answer then is to introduce legislation that would reduce those levels in everyone’s food supply, not necessarily to simply encourage those who can buy organic to buy organic.”